The invention provides an ion implantation semiconductor processing technique for implanting high purity ions in a semiconductor wafer substrate.
Known ion implantation methodology typically provides an ion source by bombarding a hot filament target with electrons to sputter-off ions, for example to sputter-off titanium ions from a titanium target. However, in electrically bombarding a target, everything around the target is also bombarded, and the whole processing chamber is subject to such bombardment which in turn generates impurities from the chamber walls and other surfaces therein. Implanters typically incorporate a further processing step to magnetically separate out impurities from the generated ion beam. Due to the bombardment and due to the magnetic separation, the end resultant ion beam is of very low flux density. The purer the ion beam desired, the lower the flux density.
The present invention provides a simple and effective technique for generating a high purity, high flux density ion beam for semiconductor ion implantation.